Chlorthalidone: What is it? Indications, Dosage, Side Effects and Precautions

It is a monosulfamic diuretic that differs chemically from thiazide diuretics in that a double ring system is incorporated into its structure.

Chlorthalidone is an antihypertensive / diuretic given in 15 mg tablets for oral use.

It is a racemic mixture of 2-chloro-5- (1-hydroxy-3-oxo-1-isoindolinyl) benzenesulfonamide, with the following structural formula:

  • Chlorthalidone is practically insoluble in water, in ether and in chloroform, soluble in methanol, slightly soluble in alcohol.
  • The inactive ingredients are colloidal silicon dioxide, lactose, magnesium stearate, microcrystalline cellulose, povidone, sodium starch glycolate.

What are the possible side effects of Chlorthalidone?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue or throat.

Stop using this medication and call your doctor immediately if you have any of these serious side effects:

  • Dry mouth.
  • However.
  • Sickness.
  • Vomiting
  • Feeling weak, sleepy, restless or dizzy.
  • Fast or uneven heartbeat.
  • Muscle pain or weakness
  • Urinating less than normal or nothing at all.
  • Bruising or easy bleeding.
  • Unusual weakness


It is indicated in the treatment of hypertension alone or in combination with other antihypertensive medications.

Chlorthalidone is indicated as adjuvant therapy in the edema associated with congestive heart failure, liver cirrhosis and therapy with corticosteroids and estrogens.

Chlorthalidone has also been found useful in edema due to various forms of renal dysfunction, such as nephrotic syndrome , acute glomerulonephritis and chronic renal failure .

Use in pregnancy

The usual use of diuretics in an otherwise healthy woman is inappropriate and exposes the mother and the fetus to unnecessary risks. Diuretics do not prevent the development of toxemia of pregnancy and there is no satisfactory evidence that they are useful in the treatment of developed toxemia.

Edema during pregnancy can arise from pathological causes or from the physiological and mechanical consequences of pregnancy. Chlorthalidone is indicated in pregnancy when the edema is due to pathological causes, as it occurs in the absence of pregnancy.

The dependent edema in pregnancy resulting from the restriction of the venous return by the expanded uterus is adequately treated through the elevation of the lower extremities and the use of a support hose; The use of diuretics to reduce intravascular volume in this case is illogical and unnecessary.

Dosage and administration

Therapy should be initiated at the lowest possible dose and then adjusted according to the patient’s individual response. A single dose administered in the morning with food is recommended; divided doses are unnecessary.


Therapy in most patients should be started with a single daily dose of 15 mg. If the response is insufficient after an adequate test, the dose can be increased to 30 mg and then to a single daily dose of 45-50 mg.

If additional control is required, the addition of a second antihypertensive drug is recommended. The increases in serum uric acid and the decreases in serum potassium are related to the dose in the range of 15-50 mg / day and more.


Initiation: adults, initially 30 to 60 mg daily or 60 mg every other day. Some patients may require 90 to 120 mg at these intervals or up to 120 mg daily. However, levels above this level generally do not produce a greater response.

Maintenance: Maintenance doses can often be lower than the initial doses and should be adjusted according to the individual patient. The effectiveness is maintained during continuous use.

Presentation and storage

  • White, kidney-shaped, m / 024-encoded tablets containing 15 mg of Chlorthalidone in bottles.
  • Storage: store below 30 ° c (86 ° f).

How does this medication work? What will he do for me?

Chlorthalidone belongs to the group of medicines called diuretics. It is also an antihypertensive. This medication is used to treat fluid retention (edema) that occurs with congestive heart failure and liver and kidney disorders .

It is also used alone or in combination with other medications to treat high blood pressure. Chlorthalidone works by causing the body to lose excess water and salt.

Who should not take this medicine?

Do not take Chlorthalidone if you:

  • It is allergic to Chlorthalidone, sulfonamides, thiazides or any of the components of the medication.
  • They can not produce urine.
  • Have a severe liver disorder.
  • If the passage of urine continues to increase over time during the treatment of severe progressive kidney disease, Chlorthalidone should be discontinued.

Your pharmacist can advise you on the management of side effects.

Pay attention to:

  • Decreased sexual capacity.
  • Diarrhea.
  • Dizziness or lightheadedness, especially when getting up from a sitting or lying position.
  • Headache.
  • Increased sensitivity of the skin to sunlight.
  • Loss of appetite
  • Nausea.
  • Stomachache.
  • Vertigo (spinning sensation)
  • Vomiting

Check with your doctor as soon as possible if you experience any of the following side effects:

  • Black, tarry stools.
  • Blood in the urine or in the stool.
  • Cough or hoarseness.
  • Fever or chills
  • Pain in the joints.
  • Lumbar or lateral pain.
  • Painful or difficulty urinating.
  • Identify red spots on the skin.
  • Skin rash or urticaria.
  • Stomach pain (severe) with nausea and vomiting.
  • Unusual bleeding or bruising
  • Yellow eyes or skin
  • Signs and symptoms of too much potassium loss:
  • Dry mouth.
  • Increased thirst.
  • Irregular heartbeat.
  • Mood or mental changes.
  • Muscle cramps or pain.
  • Nausea or vomiting
  • Unusual tiredness or weakness
  • Weak pulse

Signs and symptoms of too much sodium loss:

  • Confusion.
  • Convulsions
  • Decrease in mental activity.
  • Irritability.
  • Muscle cramps.
  • Unusual tiredness or weakness

Some people may experience side effects other than those listed. Consult your doctor if you notice any symptoms

This worries you while taking this medication.

Are there other precautions or warnings for this medicine?

The proper precautions should be taken before using this product, always with the advice of a doctor whether pregnant, in the process of breastfeeding, should provide all this information in your query to identify timely alternatives and recommended doses for you.

Some of the most important aspects are:

  • Cholesterol: You may increase your cholesterol and triglyceride levels when you take Chlorthalidone. Your doctor will monitor your cholesterol and triglyceride levels with blood tests while taking this medication.
  • Dizziness / slower reaction: due to dizziness and a delay reaction time are possible side effects of taking Chlorthalidone, especially at the beginning of therapy, you should see how the medication affects you before operating machines or driving motor vehicles.
  • Balance of fluids and electrolytes: the levels of electrolytes in your body such as potassium, sodium, magnesium and chloride can be reduced by the use of Chlorthalidone. Your doctor will check periodically if they are in balance and a potassium supplement may be necessary.
  • Warning signs or symptoms of fluid and electrolyte imbalance include:confusion, drowsiness, dry mouth, low and strenuous blood pressure, muscle aches or cramps, muscle fatigue, nausea and vomiting, cardiac arrhythmias, spasms, seizures, loss of sensitivity.

If you experience any of these symptoms, contact your doctor.

To avoid low potassium levels, eat foods rich in potassium (eg, bananas, dried figs, dates, prunes, nuts). If your potassium level is low, your doctor may suggest a potassium supplement.

  • Estócido: this medicine can aggravate or cause gout. People with high levels of uric acid in the blood or a history of gout should.
  • Kidney disease: If you have reduced kidney function, talk with your doctor about how this medicine can affect your medical condition.
  • Liver disease: If you have reduced liver function or progressive liver disease, talk to your doctor about how this medicine may affect your medical condition.
  • Lupus: This medication may worsen or activate the symptoms of lupus. If you experience swollen and painful joints, fever, fatigue or a rash on your nose and cheeks while taking this medication, contact your doctor.